The skin’s surface pH (pHss), commonly known as the “acid mantle,” plays a crucial role in maintaining skin barrier integrity, antimicrobial defense, and overall skin homeostasis. Disruptions in the pHss can lead to abnormalities in skin conditions such as eczema and psoriasis. Researchers addressed the need to understand the factors influencing pHss and how maintaining a balanced pH can improve skin health and alleviate symptoms of various skin pathologies. pH-balanced topical cleansers and moisturizers are considered as a potential solution for improving the skin’s structural and functional integrity by benefiting skin moisturization and the regeneration and organization of the stratum corneum (SC) barrier.
Key Points
•Origin of Skin Surface pH (pHss):
- The skin’s acid mantle results from both exogenous and endogenous mechanisms.
- Major molecular pathways contributing to SC acidification include the breakdown of filaggrin, lipid processing, and the activity of SLC9A1/NHE.
- Filaggrin breaks down into amino acids like histidine and glutamine, contributing to natural moisturizing factor (NMF) and UV protection.
•Intricate Nature of Skin Surface pH (pHss):
- pHss is influenced by endogenous factors such as anatomical site, skin hydration, sebum production, genetics, ethnicity, age, and gender.
- Exogenous factors, particularly harsh alkaline soaps, can negatively affect pHss.
Maintaining a balance of lipids, NMFs, and acidity is crucial for skin barrier function.
•Clinical Implications in Eczema:
- Eczema patients exhibit higher pHss, leading to enhanced skin barrier breakdown.
- Elevated pHss increases the activity of serine proteases, causing excessive skin barrier breakdown and SC incoherency.
- Increased S. aureus colonization and reduced antimicrobial defense are associated with elevated pH in eczema.
•Clinical Implications in Psoriasis:
- Psoriasis may involve a lower pHss compared to healthy skin, influencing protease control, water transport channels, and antimicrobial protein activation.
- Aquaporins (AQPs) and their role in water transport are affected by pH, with AQP3 expression decreased in psoriatic lesions.
- Acidification of the SC is crucial for defense against microbial invasion, with the skin microbiome differing significantly in psoriasis patients.
•Balancing Skin pH:
- pH-balanced skincare, including non-soap-based cleansers and moisturizers, is essential for maintaining the skin’s acid mantle.
- These formulations help preserve barrier function, enhance skin hydration, support the skin microbiome, and reduce skin sensitivity.
This review highlighted the complex interplay of factors influencing skin surface pH and its critical role in maintaining skin health. The novelty of this research lies in its comprehensive synthesis of the existing knowledge, consolidating the origin, nature, and role of pHss in both healthy and diseased skin1. By emphasizing the significance of pH-balanced topical formulations, this article paves the way for future research and promotes awareness among healthcare professionals and individuals regarding the importance of maintaining optimal skin pH. Future studies should focus on long-term clinical trials to validate the efficacy of pH-balanced skincare strategies across diverse populations and age groups.
Link to the study: https://www.mdpi.com/2079-9284/12/1/24
